com.healthmarketscience.rmiio
Class AbstractCloseableIOIterator<DataType>

java.lang.Object
  com.healthmarketscience.rmiio.AbstractCloseableIOIterator<DataType>

All Implemented Interfaces:

CloseableIOIterator<DataType>, IOIterator<DataType>, Closeable

Direct Known Subclasses:

ConverterIOIterator, IOIteratorPipe.Source, LineIterator

public abstract class AbstractCloseableIOIterator<DataType>
extends Object
implements CloseableIOIterator<DataType>

Convenience base class for CloseableIOIterator implementations, especially suited for use as the local iterator for a RemoteIteratorServer instance. This implementation manages the closing of the local resources through three separate mechanisms. The close() method will be called:

• by the next() method when the IOIterator.hasNext() method starts returning false
• when the close method is called directly (duh)
• if used with a RemoteIteratorServer, when the server is shutdown

This three-pronged attack provides a pretty strong guarantee that the local resources will be closed at some point in time. Note that the implementation of the close() method will call the closeImpl() method at most once. Extraneous invocations will be ignored.

Author:

James Ahlborn

Nested Class Summary

Nested classes/interfaces inherited from interface com.healthmarketscience.rmiio.CloseableIOIterator

CloseableIOIterator.Adapter<DataType>

Constructor Summary

AbstractCloseableIOIterator()

Method Summary

void	close()
protected abstract void	closeImpl() Does the actual closing of the local resources.
DataType	next() Returns the next element in the iteration.
protected abstract DataType	nextImpl() Does the actual work of the next() method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.healthmarketscience.rmiio.IOIterator

hasNext

Constructor Detail

AbstractCloseableIOIterator

public AbstractCloseableIOIterator()

Method Detail

next

public final DataType next()
                    throws IOException

Description copied from interface: IOIterator

Returns the next element in the iteration.

Specified by:

next in interface IOIterator<DataType>

Throws:

IOException

close

public final void close()

Specified by:

close in interface Closeable

nextImpl

protected abstract DataType nextImpl()
                              throws IOException

Does the actual work of the next() method. Will only be called if IOIterator.hasNext() is currently returning true.

Throws:

IOException

closeImpl

protected abstract void closeImpl()

Does the actual closing of the local resources. Will be called at most once by the close() method regardless of how many times that method is invoked.

Note, this method does not throw IOException because it can be called in a variety of different scenarios and throwing an IOException would be useless in many of them (and often, failure to close is merely a nuisance, not a cause for failure).